<!DOCTYPE html>
<div style="width:100px; height:100px; perspective:100px; background:red;">
  <div style="position:fixed; left:25px; top:25px; width:50px; height:50px; transform:translateZ(50px); background:green;"></div>
</div>
This test verifies CSS perspective correctly applies to fixed-position descendants. The test passes if a 100x100 green box completely occludes the red box behind.